The role of androgens in the erectile response: A 1999 perspective

Evidence from several laboratories strongly supports a critical role for an drogens in the maintenance of the mammalian erectile response. In animal st udies, androgens appear to act at the end-organ level (i.e., corporal tissu e and vasculature), as well as in the portions of the nervous system which mediate erection. Particularly in the rat model, androgens act centrally to support copulatory behavior and peripherally to maintain the production of nitric oxide and support the veno-occlusive mechanisms, Other studies sugg est that alternative, non-NO-dependent, pathways may also be androgen sensi tive. However, despite this expanding knowledge base about how androgens ac t in the erectile response in laboratory animals, the recent studies have n ot greatly clarified the role of androgens in human penile erection. There does not seem to be a strong cause and effect relation between blood androg en concentrations and erectile function; even in severely hypogonadal men, the erectile response is not always lost, and testosterone treatment of hyp ogonadal men with erectile dysfunction does not necessarily restore lost er ectile function. In addition, different types of erection (nocturnal, in re sponse to visual sexual stimulation, in response to sexual partner) may req uire different degrees of androgenic support.